The present invention relates to a set of floaters or buoys for flexible submarine pipes.
These submarine pipes are intended for the transport of hydrocarbons. The pipes are generally spaced out in the form of a catenary between a sea floor installation and a surface installation.
In deep water, when the sea floor and the surface are very far apart, submarine pipes are subjected to considerable tensile forces which are limited in part by the presence of buoys or floaters. These buoys are generally installed one after the other on selected sections of the submarine pipe and are maintained in position by clamps around the pipe, in such a way as to absorb at least a part of the tensile forces which act on the pipe and, by the same token, on the surface installation.
U.S. Pat. No. 6,270,387 describes a buoy or floater formed from a cylindrical sleeve in two parts. The sleeve has a central transcurrent hole to permit the passage of the pipe, and the sleeve is split in the axial direction to form two parts which are joined together in relation to each other around a generating line of the cylindrical form. A clamp is divided into two half-clamps that are respectively immovably attached to the two sleeve parts and are intended to be connected to each other so as to cause the two sleeve parts to be locked together and around the submarine pipe. These sleeves are mutually independent, and they are fitted on the section of the pipe in conjunction with the installation of the latter between the sea floor installation and the surface installation.
One disadvantage associated with the fitting of these clamps around the submarine pipe lies in the fragility of the surface layers of the said pipe. In fact, these are covered with a soft foam isolation layer, and it is accordingly necessary to provide a more rigid insert in place of the foam at the point at which it is proposed to fit the clamp in such a way as to prevent compression of the foam, which would otherwise flow.
A further drawback associated with the above device is that the translational displacement of these floaters along the submarine pipe, for example in order to adjust the distribution of the tensile forces, and in the event that this may not have been sufficiently well evaluated, requires that submarine pipe be raised to the surface in order to readjust the positions of all the cylindrical sleeves. This operation requires at the very least that all the clamps be released, that each of the floaters is caused to slide one after the other towards a new section of the pipe, and that all the clamps are then retightened.
One problem which is encountered in this case, and which the present invention proposes to resolve, is to make available a set of buoys or floaters which permits reduction in the number of operations necessary for the displacement of the set of buoys or floaters along the submarine pipe and which consequently permits a reduction in the global intervention time.